Re: [pysnmp-users] Bug in 3.3.4 snmpwalk.py?

[Mike C. F. <mcf...@ro...>]

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Ilya Etingof wrote:

>Yeah, that first GET request has been added to make snmpwalk.py behaving
>closer to Net-SNMP's snmpwalk. This has been implemented to do GET
>unconditionally and not to ignore [possible] errors so that's buggy.
>
>I've just re-worked the snmpwalk*.py code to fire GET only when
>instructed from command line (-Ci) e.g. in the same way as it's done in
>Net-SNMP. Please, try it out (CVS rev 1.3.2.19) and let me know in case of
>any probs:
>  
>
Seems to fix that problem.  You'll want to use a slightly more involved 
check for "is it an increasing OID value":

11:03:08 mcfletch@cmon:~/pysnmp-3.3.4/examples $ python snmpwalk.py 
172.16.0.1 public .1.3.6.1.2.1.10.127.1.3.3.1.3
.1.3.6.1.2.1.10.127.1.3.3.1.3.1  --->  '172.16.9.125'
.1.3.6.1.2.1.10.127.1.3.3.1.3.2  --->  '172.16.6.38'
.1.3.6.1.2.1.10.127.1.3.3.1.3.3  --->  '172.16.2.229'
.1.3.6.1.2.1.10.127.1.3.3.1.3.4  --->  '172.16.4.12'
.1.3.6.1.2.1.10.127.1.3.3.1.3.5  --->  '172.16.10.127'
.1.3.6.1.2.1.10.127.1.3.3.1.3.6  --->  '172.16.12.175'
.1.3.6.1.2.1.10.127.1.3.3.1.3.7  --->  '172.16.10.140'
.1.3.6.1.2.1.10.127.1.3.3.1.3.8  --->  '172.16.118.245'
.1.3.6.1.2.1.10.127.1.3.3.1.3.9  --->  '172.16.110.247'
Error: OID not increasing:  [('.1.3.6.1.2.1.10.127.1.3.3.1.3.9', 
'.1.3.6.1.2.1.10.127.1.3.3.1.3.10')]
11:03:19 mcfletch@cmon:~/pysnmp-3.3.4/examples $

i.e. str(10) < str(9) lexically.  Line 164:173 in the source, I think 
this is approximately what you want (untested as of yet, as I'm not sure 
which restriction is actually intended):

def cmpOID( x, y ):
    """just checks if we're past end of table"""
    x = x.split('.')
    y = y.split('.')
    return y[:len(x)-1] == x[:-1]

or

def cmpOID( x, y ):
    """converts to integers and does increasing-numbers check"""
    x = map(int, x.split('.'))
    y = map(int, y.split('.'))
    return y > x

or (from my current code):

        if suffix:
            sentinel = oids[0].split('.')
            sentinel = sentinel[:-suffix]
            sentinel = ".".join(sentinel)
        else:
            sentinel = oids[0]
...
            if not testOID.startswith( sentinel ):
                break

but that's a very different check for "end-of-table" which assumes that 
the first OID doesn't run out before everything else does, (and does no 
always-increasing-numbers check).

Enjoy,
Mike

_______________________________________
  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://members.rogers.com/mcfletch/